Chapter 5.1, Problem 26ES

Let $A$ denote the area between the graph of $f\left(x\right)=1/x$ and the interval $\left[1,2\right]$ , and let $B$ denote the area between the graph of $f$ and the interval $\left[\frac{1}{2},1\right]$ . Explain geometrically why $A=B$ .